1. Cross Reference to Related Applications
Reference is made to commonly assigned, copending U.S. Pat. Applications Ser. No. 751,912 entitled CHEMICAL ANALYZER, filed in the names of Louis C. Nosco, Anthony P. DiFulvio and Henry S. Adamski on Dec. 17, 1976, now abandoned; Ser. No. 912,665 entitled CONTAINER WITH ARTICLE POSITIONING ELEMENT, filed concurrently herewith in the names of R. G. Covington, S. H. Miller and A. J. Tucker; and Ser. No. 912,288 entitled ARTICLE CONTAINER, filed concurrently herewith in the names of R. G. Covington and S. H. Miller.
2. Field of the Invention
The present invention relates to article containers from which individual articles can be sequentially removed from stacks of articles received in the containers.
3. Description of the Prior Art
In recent years, a number of automated systems have been developed for carrying out quantitative chemical analysis of fluid samples. While many of the commercially available systems utilize liquid reagents and require analyzer equipment having intricate solution handling and transport capabilities, one biological fluid analyzing apparatus in which discrete test slides containing individual dry reagents are metered through the apparatus to receive a drop of biological fluid to be tested is described in commonly assigned, co-pending U.S. Pat. Application Ser. No. 751,912, entitled CHEMICAL ANALYZER filed on Dec. 17, 1976.
As described in that application, the test slides are stacked in containers also called cartridges. Each slide in a particular container has the same, appropriate reagent for a particular test, such as for example a reagent for testing glucose in blood serum. Other containers might house slides for other tests. One or more containers may be received in an appropriate nest of the analyzing apparatus with a spring biased plunger arranged to engage the stack of slides through an opening in the container to urge the slides forwardly toward a dispensing station at one end of the container.
A push blade in the analyzing apparatus enters the container at the dispensing station to remove the leading slide from the container by pushing it through a slot in the container wall. The remaining slides are moved forwardly in the container by the plunger as each preceding slide is removed.
It is foreseeable that, during the operation of such analyzing apparatus, situations might occur in which it would be desirable to take a container from the apparatus nest after some, but not all, of the slides have been removed therefrom. Such situations might include instances wherein a different biological test requiring a different reagent is to be conducted or wherein the slides are to be stored in controlled conditions at the end of a work day. Upon such removal of a container from the nest, the apparatus plunger no longer urges the remaining slides toward the container's dispensing station. As such, the slides would be free to move about within the container; possibly becoming disoriented and causing jams when the container is again loaded into the analyzing apparatus nest.
Accordingly, it has been suggested to provide the container with a stack positioning element behind the last slide. The element includes an anti-backup member which cooperates with ratchet teeth on the container walls such as shown in U.S. Pat. Application Ser. No. 912,665 entitled CONTAINER WITH ARTICLE POSITIONING ELEMENT, filed concurrently herewith in the names of R. G. Covington, S. H. Miller and A. J. Tucker. The apparatus plunger pushes against the element, which in turn ratchets forwardly in a direction to push against the slides to sequentially advance the slides to the dispensing station of the container. When a container having such stack positioning element is removed from the nest of the analyzing apparatus, the element prevents the slides from moving away from the container's dispensing station.
While such a stack positioning element would work to prevent disorientation of the slides, it would also increase the resistance to movement of the slides by the apparatus plunger. A major portion of such additional resistance would be caused by the engagement of the anti-backup member with the ratchet teeth. The additional resistance can, of course, be offset by a similar increase in the force applied by the plunger, but that increase would increase the force to be overcome upon loading full containers into the analyzer apparatus. Perhaps the most serious effect of increasing the plunger force would be the increased resistance encountered by the push blade when it is activated to push the foremost slide from the stack.